[FIR] Avoid collections copying in FirSymbolProvider

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/JavaSymbolProvider.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.fir.expressions.builder.*
 import org.jetbrains.kotlin.fir.java.declarations.*
 import org.jetbrains.kotlin.fir.resolve.constructType
 import org.jetbrains.kotlin.fir.resolve.providers.AbstractFirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.resolve.scopes.wrapScopeWithJvmMapped
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.impl.lazyNestedClassifierScope
@@ -62,8 +63,8 @@ class JavaSymbolProvider(
         content: KotlinClassFinder.Result.ClassFileContent?,
     ): JavaClass? = facade.findClass(JavaClassFinder.Request(classId, previouslyFoundClassFileContent = content?.content), searchScope)
 
-    override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> =
+    @FirSymbolProviderInternals
-        emptyList()
+    override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {}
 
     override fun getNestedClassifierScope(classId: ClassId): FirScope? {
         val symbol = this.getClassLikeSymbolByFqName(classId) ?: return null

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/deserialization/KotlinDeserializedJvmSymbolsProvider.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.fir.references.builder.buildResolvedNamedReference
 import org.jetbrains.kotlin.fir.references.impl.FirReferencePlaceholderForResolvedAnnotations
 import org.jetbrains.kotlin.fir.resolve.firSymbolProvider
 import org.jetbrains.kotlin.fir.resolve.providers.AbstractFirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.resolve.providers.getClassDeclaredCallableSymbols
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.KotlinScopeProvider
@@ -384,8 +385,9 @@ class KotlinDeserializedJvmSymbolsProvider(
             }
     }
 
-    override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> {
+    @FirSymbolProviderInternals
-        return getPackageParts(packageFqName).flatMap { part ->
+    override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
+        getPackageParts(packageFqName).flatMapTo(destination) { part ->
             loadFunctionsByName(part, name) + loadPropertiesByName(part, name)
         }
     }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/FirSymbolProvider.kt

@@ -23,8 +23,10 @@ import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 
-abstract class FirSymbolProvider : FirSessionComponent {
+@RequiresOptIn
+annotation class FirSymbolProviderInternals
 
+abstract class FirSymbolProvider : FirSessionComponent {
     abstract fun getClassLikeSymbolByFqName(classId: ClassId): FirClassLikeSymbol<*>?
 
     fun getSymbolByLookupTag(lookupTag: ConeClassLikeLookupTag): FirClassLikeSymbol<*>? {
@@ -44,7 +46,13 @@ abstract class FirSymbolProvider : FirSessionComponent {
         }
     }
 
-    abstract fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>>
+    @OptIn(ExperimentalStdlibApi::class, FirSymbolProviderInternals::class)
+    open fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> {
+        return buildList { getTopLevelCallableSymbolsTo(this, packageFqName, name) }
+    }
+
+    @FirSymbolProviderInternals
+    abstract fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name)
 
     abstract fun getNestedClassifierScope(classId: ClassId): FirScope?
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirBuiltinSymbolProvider.kt

@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.fir.deserialization.FirDeserializationContext
 import org.jetbrains.kotlin.fir.deserialization.deserializeClassToSymbol
 import org.jetbrains.kotlin.fir.resolve.getOrPut
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.KotlinScopeProvider
 import org.jetbrains.kotlin.fir.scopes.impl.nestedClassifierScope
@@ -243,10 +244,11 @@ class FirBuiltinSymbolProvider(val session: FirSession, val kotlinScopeProvider:
 
     private fun FunctionClassDescriptor.Kind.classId(arity: Int) = ClassId(packageFqName, numberedClassName(arity))
 
-    override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> {
+    @FirSymbolProviderInternals
-        return allPackageFragments[packageFqName]?.flatMap {
+    override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
+        allPackageFragments[packageFqName]?.flatMapTo(destination) {
             it.getTopLevelCallableSymbols(name)
-        } ?: emptyList()
+        }
     }
 
     override fun getNestedClassifierScope(classId: ClassId): FirScope? {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirCloneableSymbolProvider.kt

@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.fir.declarations.builder.buildRegularClass
 import org.jetbrains.kotlin.fir.declarations.builder.buildSimpleFunction
 import org.jetbrains.kotlin.fir.declarations.impl.FirDeclarationStatusImpl
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.FirScopeProvider
 import org.jetbrains.kotlin.fir.symbols.CallableId
@@ -65,9 +66,8 @@ class FirCloneableSymbolProvider(session: FirSession, scopeProvider: FirScopePro
         return if (classId == CLONEABLE_CLASS_ID) klass.symbol else null
     }
 
-    override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> {
+    @FirSymbolProviderInternals
-        return emptyList()
+    override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {}
-    }
 
     override fun getNestedClassifierScope(classId: ClassId): FirScope? {
         return null
@@ -76,4 +76,4 @@ class FirCloneableSymbolProvider(session: FirSession, scopeProvider: FirScopePro
     override fun getPackage(fqName: FqName): FqName? {
         return null
     }
-}
+}

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirCompositeSymbolProvider.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.resolve.providers.impl
 
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassLikeSymbol
@@ -19,6 +20,11 @@ class FirCompositeSymbolProvider(val providers: List<FirSymbolProvider>) : FirSy
         return providers.flatMap { it.getTopLevelCallableSymbols(packageFqName, name) }
     }
 
+    @FirSymbolProviderInternals
+    override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
+        destination += getTopLevelCallableSymbols(packageFqName, name)
+    }
+
     override fun getNestedClassifierScope(classId: ClassId): FirScope? {
         return providers.firstNotNullResult { it.getNestedClassifierScope(classId) }
     }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirDependenciesSymbolProviderImpl.kt

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.dependenciesWithoutSelf
 import org.jetbrains.kotlin.fir.resolve.providers.AbstractFirSymbolProvider
 import org.jetbrains.kotlin.fir.resolve.firSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.symbols.CallableId
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
@@ -26,6 +27,11 @@ open class FirDependenciesSymbolProviderImpl(val session: FirSession) : Abstract
         }.toList()
     }
 
+    @FirSymbolProviderInternals
+    override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
+        destination += getTopLevelCallableSymbols(packageFqName, name)
+    }
+
     override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> {
         return topLevelCallableCache.lookupCacheOrCalculate(CallableId(packageFqName, null, name)) {
             dependencyProviders.flatMap { provider -> provider.getTopLevelCallableSymbols(packageFqName, name) }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirProviderImpl.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
 import org.jetbrains.kotlin.fir.resolve.providers.FirProvider
 import org.jetbrains.kotlin.fir.resolve.providers.FirProviderInternals
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.KotlinScopeProvider
 import org.jetbrains.kotlin.fir.scopes.impl.nestedClassifierScope
@@ -60,6 +61,11 @@ class FirProviderImpl(val session: FirSession, val kotlinScopeProvider: KotlinSc
             return (state.callableMap[CallableId(packageFqName, null, name)] ?: emptyList())
         }
 
+        @FirSymbolProviderInternals
+        override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
+            destination += getTopLevelCallableSymbols(packageFqName, name)
+        }
+
         override fun getNestedClassifierScope(classId: ClassId): FirScope? {
             return (getFirClassifierByFqName(classId) as? FirRegularClass)?.let {
                 nestedClassifierScope(it)

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/providers/FirIdeProvider.kt

@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
 import org.jetbrains.kotlin.fir.resolve.providers.FirProvider
 import org.jetbrains.kotlin.fir.resolve.providers.FirProviderInternals
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
+import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProviderInternals
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.KotlinScopeProvider
 import org.jetbrains.kotlin.fir.symbols.impl.FirAccessorSymbol
@@ -115,6 +116,11 @@ internal class FirIdeProvider(
         override fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): List<FirCallableSymbol<*>> =
             providerHelper.getTopLevelCallableSymbols(packageFqName, name)
 
+        @FirSymbolProviderInternals
+        override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
+            destination += getTopLevelCallableSymbols(packageFqName, name)
+        }
+
         override fun getPackage(fqName: FqName): FqName? =
             providerHelper.getPackage(fqName)